Probes for making electrical contact to a device under test (DUT) are typically resilient devices that deform in a controllable manner in use. Probe deformation can perform various functions, such as providing a suitable scrub motion between probe tip and contact pad to facilitate making a reliable electrical contact. The shape of a probe has a significant effect on its deformation properties, and accordingly many kind of probe shapes have been considered in the art. Representative examples of known probe shapes include U.S. Pat. Nos. 6,707,311, 6,482,013, 6,278,284, 5,832,601, 6,956,389, 6,677,245, and US 2003/0027423.
Various probe fabrication methods have been employed to make such probes. One of these methods is referred to as micro-fabrication, and entails building up a probe (or probe array) by deposition of appropriately patterned layers having probe material and sacrificial material, such that eventual removal of the sacrificial material exposes the fabricated probe(s). Micro-fabrication approaches typically impose an overall height limit on the fabricated probe. A typical height limit for micro-fabrication is on the order of 0.8 mm. The existence of some such limit is unsurprising, since deposition of an unlimited number of layers is unlikely to be practical.
Probes provided by micro-fabrication have been considered in the art. Examples include the probes of US 2005/0189958,U.S. Pat. No. 6,917,525, 6,218,203, and U.S. Pat. No. 6,027,630, where several zigzag and folded probe geometries are considered. Many of these probe designs can be regarded as a scaling of known probe geometries to comply with the vertical height limit of probe micro-fabrication.
However, we have found that such scaling of known probe geometries to comply with the height limit of probe micro-fabrication tends to provide probes having unfavorable performance characteristics. In particular, it is difficult to obtain sufficient lateral scrub motion from conventional probe geometries scaled to comply with a height limit on the order of 0.8 mm.
Accordingly, it would be an advance in the art to provide a probe geometry for providing improved lateral scrub motion while complying with a vertical height limit.